1.Field of the Invention
The present invention is related to a communication-device, and more particularly to an antenna system for a communication device.
2.Description of the Related Art
Communication devices, such as radiotelephones, are being driven by the marketplace and technology towards smaller, more compact sizes and form factors. Consumer and user demand has continued to push a dramatic reduction in the size of such communication devices. The reduction in size provides additional challenges to the device designers to achieve adequate antenna electrical performance.
To create a more compact package, many communication devices in use today have incorporated as part of the overall communication device a flip assembly housing (also known as a clamshell assembly). A flip assembly housing typically consists of two or more housing portions that can each contain one or more printed circuit boards (PCBs) with electronic components, audio devices, cameras, visual displays, and the like, as well as wiring to connect the electronic components together. In some communication devices, one housing portion is a hinged cover that closes to make the communication device more compact and to protect a keypad or other user interface located on a second housing portion from inadvertent entries. Typically, one housing rotates relative to the other housing in a plane perpendicular to the plane of the other housing. As an example, a communication device such as a radiotelephone can comprise two planar elements coupled by a hinge. When the radiotelephone is not in use, the two planar elements are closed and lie in parallel. When the radiotelephone is in use, the two planar elements are opened in relation to each other, exposing such elements as a key pad, display, microphone and/or speaker.
Each communication device includes an antenna coupled to a transceiver to perform the receiving and transmitting functions required of the communication device. Typically, the antenna is not the only structure that radiates the energy within a communication device. For example, a portion of the energy is radiated from the grounding structure (for example, a PCB ground) connected to the source of energy (for example, a generator). When the physical length of the grounding structure is not a multiple of the half (½) wavelength of the frequency of the radiated energy, the efficiency of the radiating structure can diminish. Testing has shown, for example, a degradation of performance of small clamshell phones at frequencies further away from half (½) wavelength compared to larger phones.
Further, it has been observed that the presence of a user's body, for example, a finger holding a radiotelephone, can cause a degradation of performance. The antenna is detuned by the finger touch grip and degrades the performance.